<polymer-element name="x-sheets">
  <style>
    .red1 {
      background: tomato;
    }
  </style>
  <template>
    <link rel="stylesheet" href="sheet1.css">
    <link rel="stylesheet" href="sheet2.css">
    <div id="red" class="red1">red</div>
    <div id="blue" class="blue2">blue</div>
    <div id="yellow" class="yellow12">yellow12</div>
  </template>
  <script>Polymer('x-sheets')</script>
</polymer-element>
